Edward There is no "common practice" for BGA's. It depends on the PWB shop and customer requirements. Also on the BGA density (of connnections). Microvias range in size from 2-8 mils diameter. Plating is typically electroplated copper (although the photovia process is being demonstrated by conductive inks provided by ORMET). Most don't require microvias below 4-5 mils (because of the cost of manufacturing). There is much more detail to go into, but your question is vague. Do you need to locate a laser drill shop, board supplier, etc? Or is this educational? Shannah Tovah -----Original Message----- From: edward Edward Szpruch <[log in to unmask]> To: [log in to unmask] <[log in to unmask]> Date: Tuesday, September 14, 1999 5:06 AM Subject: [TN] BGA micro-blind vias >Hi, >What is the common practice concerning blind-microvias located on BGA pads: >a) open ? ( 2-3 mills diameter, 2 mills deep) >b) filled with what ( fill materials,LPI solder mask)? >c) filled with electroplated copper ? >Pls advice > >Edward Szpruch >Eltek , Manager of Process Engineering >P.O.Box 159 ; 49101 Petah Tikva Israel >Tel ++972 3 9395050 , Fax ++972 3 9309581 >e-mail [log in to unmask] > >############################################################## >TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c >############################################################## >To subscribe/unsubscribe, send a message to [log in to unmask] with following text in >the body: >To subscribe: SUBSCRIBE TECHNET <your full name> >To unsubscribe: SIGNOFF TECHNET >############################################################## >Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional >information. >If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or >847-509-9700 ext.5365 >############################################################## > ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################